Why is this medication prescribed?

Levonorgestrel is used to prevent pregnancy after unprotected sexual intercourse (sex without any method of birth control or with a birth control method that failed or was not used properly [e.g., a condom that slipped or broke or birth control pills that were not taken as scheduled]). Levonorgestrel should not be used to prevent pregnancy on a regular basis. This medication is to be used as an emergency contraceptive or backup in case regular birth control fails or is used incorrectly. Levonorgestrel is in a class of medications called progestins. It works by preventing the release of an egg from the ovary or preventing fertilization of the egg by sperm (male reproductive cells). It also may work by changing the lining of the uterus (womb) to prevent development of a pregnancy. Levonorgestrel may prevent pregnancy, but it will not prevent the spread of human immunodeficiency virus (HIV, the virus that causes acquired immunodeficiency syndrome [AIDS]) and other sexually transmitted diseases.

How should this medicine be used?

Levonorgestrel comes as a tablet to take by mouth. If you are taking Plan B® One-Step, take one tablet as soon as possible within 72 hours after unprotected sexual intercourse. If you are taking Next Choice®, take one tablet as soon as possible within 72 hours after unprotected sexual intercourse and take a second dose 12 hours later. Levonorgestrel works best if it is taken as soon as possible after unprotected sexual intercourse. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take levonorgestrel exactly as directed.

Levonorgestrel is available as a nonprescription medication for women 17 years of age and older, and by prescription only for women younger than 17 years of age. If you are younger than 17, you will need to talk to a doctor to get a prescription for levonorgestrel. If you are 17 years of age or older you can buy levonorgestrel at a pharmacy. Levonorgestrel is kept behind the pharmacy counter and you will need to show the pharmacist your driver's license or other government-issued identification that shows your age in order to purchase the medication.

If you vomit less than 2 hours after you take a dose of levonorgestrel, call your doctor. You may need to take another dose of this medication.

Because you can become pregnant soon after treatment with levonorgestrel, you should continue using your regular method of birth control or begin using regular birth control immediately. If you use hormonal contraceptives (birth control pills, patches, rings, implants, or injections), you should also use a barrier method (condom or diaphragm with spermicide) every time you have sex during the same menstrual cycle as you took levonorgestrel.

Other uses for this medicine

What special precautions should I follow?

Before taking levonorgestrel,

tell your doctor and pharmacist if you are allergic to levonorgestrel, any other medications, or any of the ingredients in levonorgestrel tablets. Ask your pharmacist for a list of the ingredients.

tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements, you are taking or plan to take. Be sure to mention any of the following: barbiturates such as phenobarbital or secobarbital (Seconal); bosentan (Tracleer); griseofulvin (Fulvicin-U/F, Grifulvin V, Gris-PEG); certain medications used to treat human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) including amprenavir (Agenerase), delavirdine (Rescriptor), efavirenz (Sustiva), etravirine (Intelence), fosamprenavir (Lexiva), nelfinavir (Viracept), nevirapine (Viramune), ritonavir (Norvir, in Kaletra), and saquinavir (Invirase); certain medications for seizures such as carbamazepine (Equetro, Tegretol), felbamate (Felbatol), oxcarbazepine (Trileptal), phenytoin (Dilantin, Phenytek), and topiramate (Topamax); and rifampin (Rifadin, Rimactane). Levonorgestrel may not work as well or may be more likely to cause side effects if it is taken with these medications.

tell your doctor what herbal products you are taking, especially St. John's wort.

tell your doctor if you have or have ever had any medical conditions.

tell your doctor if you are pregnant. Do not take levonorgestrel if you are already pregnant. Levonorgestrel will not end a pregnancy that has already begun.

tell your doctor if you are breast-feeding.

you should know that after you take levonorgestrel, it is normal for your next menstrual period to begin up to a week earlier or later than expected. If your next menstrual period is delayed for longer than 1 week after the expected date, call your doctor. You may be pregnant and your doctor will probably tell you to have a pregnancy test.

Some side effects can be serious. If you experience the following symptom, call your doctor immediately:

Levonorgestrel may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/Safety/MedWatch] or by phone [1-800-332-1088].

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

Symptoms of overdose may include the following:

What other information should I know?

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.